The BSE benchmark Sensex gained nearly 94 points to 19,615 in the opening trade today.The sensex was trading at 19,675 up by 135 points a short while ago. Analysts said the gain in sensex is due to sustained buying by funds and retail investors, buoyed by improved domestic economic growth. However, they said, a weakening trend on other Asian bourses following overnight losses at the US market, limited its gains.Hong Kong's Hang Seng Index was down by 0.54 per cent, while Japan's Nikkei Index lost 0.11 per cent in early trade. In the US, the Dow Jones Industrial Index ended 0.42 per cent lower yesterday.